I’m currently using SPT5425LV-W which has 0.22s/60deg speed at 4.8v and it’s kind strugle to keep up with speed above medium-high script.
I’m now looking at 2 candidates:
1 is GXServo G25 0.07s/60deg 25Kg.cm torque at 7.4v 228CNY for each
2 is GXServo X20 0.05s/60deg 20Kg.cm torque at 7.4v 285CNY for each
Now my questions are:
1.Is 20Kg.cm torque enough for my 700g onahole?
2.Is 0.07s/60deg speed enough for most high speed script?
3.If I’m choosing X20 does it worth the few dozen more CNY compare to G25?
If there are other better servos around the simular price, plz recommend to me <3
The first question would be, what exactly is limiting the OSR to keep up. Is it the speed limit (0.22s/60deg) or is it the torque? If that doesn’t sound logical, a little bit of physics: Torque is needed not only to keep a mass in place (gravity), but to accelerate it and to overcome friction. This means: If you decrease the torque, it will take longer to reach the same speed and in fact will never actually reach the 0.07s/60deg which are reached in load-free conditions.
The second question would be: What is medium-high speed?
IIRC the main servos on the OSR move approximately 60° for a full stroke. An angular speed of 0.22s/60deg would then theoretically mean that speeds of approximately 450 units/s are attainable if you’re using the full range of the OSR. With more limited output ranges, the maximal attainable scripted speed is higher (e.g. ~570 units/s if using 80% of the range). This is because the output scales the original script, so in actuality the scripted e.g. 600 units/s become 480 units/s with 80% range. (I am simplifying by not including acceleration and deceleration)
Do you know the speeds in these terms or can link to a script as an example?
For fun: 0.07s/60 deg at full range would mean ~1400 units/s which is way beyond anything reasonable.
Also: Depending on the board you are using, changing the voltage might be problematic. So take a look at that part too. But if compatible, easily possible and not too pricey I would probably increase the voltage for better performance. If you’re staying at 4.8V, then the X20 and G25 will run slower and with less torque than at 7.4V.
I don’t realy know which is the case. It apears like it doesn’t know it should go up or down and kind stuck in place sometimes move a lil then stuck again.
I don’t, mainly bc of I don’t even know what a unit means.
For reference, the part is red or orange in MFP is stuggling
Really hard to analyze from what you are saying. Can you link a script which gives you problems? Because I want to see whether the problem might come from frequency or do the problems actually arise once you get to the speed limit of the servos.
Also if you are using MFP, for analysis purposes and to eliminate some effects of filtering, please test with ‘linear’, to see whether it behaves the same. While Makima or PChip are smoother, this filtering (I’m not sure how exactly the filters are implemented) could exacerbate the effect if the movement has high frequency.
A unit is basically one percent of the movement range. I.e. the position ranges from 0 to 100 units. So doing 200 units/s would mean a stroke (bottom-top) takes 0.5s. I’m not sure about colors.
I was gonna record a video for you ,but it seems like I can’t recreate the sympton without onahole straped on.
So ig it’s having not enough torque to move to the desired position in time, so the actual angle speed is much slower when under load that’s why it behaves like having not enough speed
Ah yes, that indicates a torque limitation. This can stem from the servos themselves, but also from the electrical side if the voltage dips under load. Do you use a power bus? If so: soldered or with a clamped setup? And does the power supply have enough power?
I’m using 2 usb wires 1for serial connection 1for power supply, they both connected to the back of my computer.
So I don’t think it’s caused by voltage drops bc otherwise I would hear Windows notifying me some devices disconnected.
Power can very well be the issue here. USB3 Ports on PCs deliver up to 900mA without any further power negotiation and if even supported. USB2 Port will only deliver up to 500mA.
Anything higher will require power negotiation and compatability.
That isn’t a high power budget. If you can, can you try another 5V power supply? Some LEDs come with 5V power supplies or SmartHome/IoT Devices.
Windows may notify you if the serial device drops. but not if the servos are underpowered.
What servos can be recommended heavily depends on where you live as well. As sourcing can be very difficult in some countries/regions.
There are many discussions regarding what servos to choose. Maybe you can find some good ideas with the search. But they get expensive quickly.
Yeah I’m with nudem here. If it isn’t USB-C PD or similar (which would be surprising for a mainboard USB-Port) then you are likely massively underpowered. Changing the servos won’t do a thing, if the input power is the limiting factor.
One unnegotiated USB3 port delivers 4.5W which is completely insufficient. For reference: I use a 50W power supply for my OSR2+Twist. It is overpowered because I’m thinking of at some point building an SR6 and I’m re-using it from another project, but that is the power range to aim for.
You need a separate power supply that is plugged into an outlet or 21700 batteries (if you know how to battery). A USB power bus that is powered by your PC will not provide enough current to the servos to overcome faster speeds.
@famousindo It sounds like they are using a proper PC Power Supply for it now. And not the USB Port anymore. So power isn’t an issue. Those Servos are rated up to 5V only.
Then i would guess the servos may not have the strength required. However others may have more ideas to test first. Maybe you can save some money by not having to buy servos.
I also use minimum 35kg and not 20s or 25s. I’ve recently replaced them due to wear and tear. Now I’m using 9imod 40kg. Far quieter and less noticeable lag. You also need to adjust the delay when syncing with scripts.
40s aren’t cheap. I’ll tell you that. Ali Express has the lowest price I’ve found, but they’re still around $15 a piece. If you want quality, it will always involve more $$
